Sphere lapping machine and method



Feb. 2, 1965 H. J. THOMPSON 3,167,884

SPHERE LAPPING MACHINE AND METHOD Filed Nov. 27, 1962 9 Sheets-Sheet 1 INVENTOR HOWARD J. THOMPSON ATTORNEY FIG.

Filed Nov. 27 1962 H.'J. THOMPSON SPHERE LAPPING MACHINE AND METHOD 9 Sheets-Sheet 2 INVENTOR. HOWARD J. THOMPSON TTCRNEY Feb. 2, 1965 'H. J. THOMPSON SPHERE LAPPING MACHINE AND METHOD 9 Sheets-Sheet 3 Filed NOV. 27, 1962 INVENTOR. HOWARD J. THOMPSON ATTORNEY Feb. 2, 1965 H. J. THOMPSON 3,167,834

SPHERE LAPPING MACHINE AND METHOD Filed Nov. 27, 1962 9 Sheets-Sheet 4 IN VEN TOR 4 HOWARD J. THOMPSON AT ORNEY Feb. 2, 1965 H. J. THOMPSON SPHERE LAPPING MACHINE AND METHOD 9 Sheets-Sheet 5 Filed Nov. 27, 1962 INVENTOR HOWARD J. THOMPSON ATTORNEY Feb. 2, 1965 H. J. THOMPSON 84 SPHERE LAPPING MACHINE AND METHOD Filed Nov. 2'7, 1962 9 Sheets-Sheet 6 IN VENTOR HOWARD J. THOMPSON ATTORNEY Feb. 2, 1965 H. J. THOMPSON SPHERE LAPPING MACHINE AND METHOD 9 Sheets-Sheet 7 Filed NOV. 27 1962 mm s NP M m WT m J. a w m N I A T w T H A Y A. 3 B 4 O M I m 5 I B L 8 4 I 4 G F Feb. 2, 1965 H. J. THOMPSON SPHERE LAPPING MACHINE AND METHOD 9 Sheets-Sheet 8 Filed Nov. 27. 1962 FIG. 9,

* INVENTOR HOWARD J. THOMPSON ATTdRNgY Feb. 2, 1965 H. J. THOMPSON SPHERE LAPPING MACHINE AND METHOD Filed Nov. 27, 1962 9 Sheets-Sheet 9 INVENTOR. HOWARD J. THOMPSON ATT NEY United States Patent 3,167,884 dPEERE LAlPPlNG MACHINE AND METHQD Howard .l. Thompson, Stillwater, Minn, assignor to Honeywell End, a corporation of Delaware Filed Nov. 27, 1962, Ser. No. 240,368 14 Claims. (Cl. l--3) This invention relates to means for automatically producing spheres having a sphericity far in excess of anything commercially obtainable, even by the most careful nonautomatic process. The need for rotors which are spherical within a very few million-tbs of an inch arose in connection with ultna precise gyroscopes for'iner-tial navigation. The rotor must be spherical to a high order and sphere grinding methods hitherto satisfactory were found hopelessly inadequate for producing rotors meeting the most stringent requirements.

An object :of the invention is to provide novel means and method for automatically producing spheres of an extremely high sphericity.

Another object is to provide means for rotating a sphere about its center, which means operates inherently to produce random movement of the sphere.

A more specific object of the'invention is to provide separate lapping means including a plurality of laps to tatable about normally horizontal axes which intersect at a common point, the laps being hollow and providing the sole support for the sphere, together with means for angllarly' oscillating one of the shafts through a limited angle in a horizontal plane, and means for continuously supplying lapping slurry to the surface of the sphere.

A further object of the invention is to provide such means combined with means for biasing one of the shafts so that it tends to move out of its normal radial alignment with respect to the sphere.

Various other objects, advantages, and features of novelty, not individually enumerated above, which characterize my invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding ofthe invention, its advantages, and objects attained by its use, reference should be had to the subjoined drawing, which forms a further part hereof, and to the accompanying descriptive matter, in which I have illustrated and describeda prefenred embodiment of my invention.

In the drawing, FIGURE 1 is a top view of the apparatus, FIGURE 2 is a vertical section taken generally along the line 2-2 of FIGURE 1, FIGURE 3 is a top View of the shelf of the apparatus, FIGURE 4 and FIG- URE 9 gives linkage details, FIGURE 10 is an enlarged a sasst Fatentecl Feb. 2, 1965 to move linearly along its axis. Shaft 25 is carried in a mounting 31 which permits rotation and translation of the shaft around and along its axis, and also permits limited pivotal movement of the shaft about a point lying on the axis of shaft 25 and in the horizontal plane containing the axis of shaft 24. Shaft 26 is carried in a mounting 32 like mounting'31, and is extended to pass through a biasing device 33. Resilient members in the form of springs 34, 35, and 36 have as one of their functions to urge the shafts, and hence the laps, toward point 27, to engage the surface of the sphere and support it without necessity of any support member directly under it. As a second'function, the resilient members transmit rotation to the shafts.

Mountings 3i 32 and biasing device 33 are secured to a table top 37, to which is also removably secured a basin assembly 44} which is designed to continuously supply lapping slurry to the lowermost surface of the sphere. The table top is pnovided with an aperture 41 in Y which a support member 42 may move to cause angular oscillation of mounting member 3b through a restricted angle about point 27, so that tho ax-is of shaft 24 traces a normally horizontal plane.

Support member 42 is mounted for movement about a vertical axis provided by a bearing assembly 43 carried on a table shelf 44, and is oscillated by a motor 4-5 through a suitable mechanical linkage 46. Further motors 47, dd, and 51 are provided for causing rotation of shafts Z4, 25, and 26 respectively, about their axes, motor 47 being carried on support member 42, and'motors 50 and dlbeing mounted on shelf 44. The shelf also mounts a further motor 52 for driving an agitator. The table top is of course apertured to pass driving belts for motors 6t? and 51, and to permit operation of the agitator. The principal components outlined above will now be described in detail. 7

Mounting 31 is shown in FIGURE 4 to comprise a base plate 53, a front plate 54, a back plate 55, and side plates 56, tall welded together to form a unitary structure. Front plate 54 is bored and shouldered to receive a bearing 5'7, and "back plate 55 is bored to receive a bearing 60. A gimbal housing 61 is carried in bearings 57 and 60, and is lapertured at diametrically opposite points to receive a pair of pins 62 which pivotally carry a gimbal ring 63, the latter being apertured at diametrically opposite points to receive further pins, as suggested at 64, vto pivotally support a bushing retainer 65. The axes of pins 62 and 64 intersect at right angles on the axis of shaft 25, which is carried in \a bushing 66 held in retainer 65 by a snap ring 67. Shaft 25 is enlarged at its front end, as indicated at 7%, to mount lap 22, and carries a collar '71 which is drilled at '72 to'receive one end of spring 35: the other end of the spring is received in a similar bore 73; in resectional view along the'line lil1 of FIGURE 1, and

FIGURE 11 is a fragmentary view showing details of a portion of the apparatus, parts being broken away for clarity of illustration.

The general nature of my apparatus may be seen in with respect to the sphere.

Shafit 24 is carried in afirst mounting 30 which maintains the shaft with its axis horizontal and passing vthrou gh point 27, but perrnits it to rotate about its own axis and tainer 65. A centrally bored stop plate 74 retains'bearing and hence housing 61 place; A pulley 75 is secured externally to housing 61, for driving by a' belt 76 which extends downward throng-h apertures in baseplate 53 and table top 3'7 to be driven by a pulley '77 on the shaft of motor 50 (FIGURE 3).

FIGURES 1, 2 and 3. A sphere to be lapped, shown by" ,Mounting 32 is constructed like mounting 31, and-is driven by a belt fill from'motor 51 (FIGURE 3). Biasing device 33 is shown in FIGURES 5 and 6 to comprise a mounting bracket 31 having a large bore 82 which agrees with the inside diameter of a mounting ring 83 secured to it by suitable means A contact drum 85 ,is supand formed at the other end to engage drum 85. Device 33 is mounted on table top 37 in such a position that when shaft zen in its normal alignment, and :drum 85' is positioned centrally in ring 83, .leaf spring 92 exercises the same biasing force on shaft 26 throughout its rotation.

Mounting 3(l'is shown in FIGURES 7 and .8 to comprise a flanged base plate 90,. a front plate 91, aback plate 92, and side plates 93 welded together to form a unitary structure. Front plate 91 is bored and shouldered to receive a bearing 94, andback plate 92 is bored tov receivea bearing-95. A hollow shaft as is carried in bearings 94'and 95, the later being held in position by a stop plate97 secured to back plate92 by suitable means andlSS in which rollers 156 and l7 are carried'on pivots Mil and 161. The dimensions of member 153 are such that duringro'tation of shaft 145 rollers-156 and 157 alternately' pass through an aperture 162 in table top 37 and bored to pass shaft 24 freely. The ends of hollow shaft eare counter-bored to receive bushings ltliland fill, which are held in place by'snap rings M32 and 103 respectively. Hollow shaft as isbored to receive one end and project slightly thereabove.

a As shown in. FIGURES and 1l,'basin assembly' lt) is mounted ontable top 37 over aperture 162. ltcomprises a basin 163 "secured to a mountingplate 164 which in turn is removably fastened tothe table top by mounts ing screws 165-. -Basinl63 hasfa Vertical sidewall and a bottom'which tapers downwardly and inwardly toward 7 a large central aperture .166, the latter being closed by a .fiexible elastic diaphragm 167 secured to the under surface of basin 163 by suitable means including ,a clamp ring 170. A generallyT-shaped wear Iplate'17l of thin Phosphor bronze is clamped between ring l'm and diaof spring 34, the'other end being received in a bore in a collar 104 secured to shaft 24. A pulley W5 is secured to shaft 96 and is driven through a belt 1% by motor 47 (FIGURE Z). A dust cover M7 may be fastened to I plates 91 and 92 in any suitable fashion.

A boss-11d is secured to the bottom of stop'plate 97 and is bored to pivotally receive theshaft 111 of a handle generally. identified by reference numeral 112 and com-' prising a pair of side plates T113 joined by intermediate bars 114 and 15 and a hand grip 116. Shaft24 carries 1 a second collar 117, and under the action of spring 34,

which is normally compressed, collar 117 remains inert phragrn 167 forengagement by rollers 156 and lfii. As

shown in FIGURE 1, an'arcuateguide plate 172 is fastened to table 137 to facilitate replacement of basinassembly ld after removalfor cleaning. I

In use, basin 163 is filled with lappingslurry' and suitable laps are mounted on shafts 24,25, and 26. .Handle 116 is displacedto the, right as. seen in FIGURE '1, a sphere to be lapped is placed'again'st laps 22 and 23, and handle 116 is released. Due to the action of springs 34, 35, and 35, the sphere is supported solely between laps. Motor '52 .is set'in operationand causes slurry to be" splashed upwardly against the under'surface of the gagement with bar 1151' When handle 212 is inechani cally pivoted in a counterclockwise direction about member llll, bar 115 acts oncollar 117 to displace shaft 24 to the left as seen in FIGURE 7.. The lap carried on shaft 24 can. thus-be displaced sufficiently to allow a sphere to be inserted into position.

Motor 47 isrnounted on the bottom 12% of bracket 42 or removed from the lapping havingside walls 122 and 123 connected by end plates 124 and 125 and top plates 126 and 127, all welded to-. getherto form a unitary structure. The top plates support base plate 5%? of mounting 3%, setting between the:

flanges thereof, and being secured thereto by suitable fastening means. Base plate Ellis apertured and plates 126 and l2? are spaced to permit the passage of belt 106 from pulley 195 to a drive. pulley 1% on the shaft of motor 47. The latter is preferably a reversiblevariable speed motor, as are motors 45, 5d, 51 and 52. 1

sphere.

Control of the rotation may be exerted by varymotors 45,. 47, 5t), and 51, and the positionxof drum 85 in ring 83. My apparatus has been found to produce a,

more nearly random sphere" movement'than apparatus heretofore have -known, and this is .believed to-be .due in part to the fact that the biasing effect, of gravity has 1 been removed by so-arranging the structure that neither Bracket 42 is mounted on a bearingassembly :43 comprising a pivotv member .131 having an upper-flange .por-

tion. 132 bolted to the underside of the bracket and a pivot 333 extending vertically-downward therefrom. The

shaft is carried in bearings i34- and l contained in a. socket lile secured by a flange 137m table shelf i l and closed by a cap. member. 143; They axis. of pivot .133

supporting means nor lapping means engage the sphere to be grounded from beneath at its centen. 5

Numerous objects and advantages of. my invention havebeen set forth in the; foregoing description, together 'with detailsof the: structure and function-of the invention, and the novel featuresthereof are-pointed out in" the appended claims. The disclosureghowever, isillus-J trative only, 'and'I may make changes in detail, especially in matters of shape, siz'e,' and anrangement of parts, within the principle of the invention, to the full extent indicated by, the broad generalmeaning of the terms in which the appended claims are expressed. Lelaimes rnyinventiorn; I 1.'Means for causing random rotation of, a sphere "comprising,- in combination: alplurality of hollowfricextends vertically to pass through the point of normal intersection of the axes'of shafts 2e, 25 and 26. i lvlotorf lS is rriountedgrvithits'axis vertical, on .a bracket 135 suspended under an: aperture 137 in [table shelf 44: it is connected to oscillate bracket 42 throughi a limited anglejabout the axis of bearing assembly43'by means of linkage 46 shown in FIGUREQ. A disc 140 is mountedon the shaft of motorA'S', and to this disc'is adjustablyattached a slotted plate -l4-lcarrying a pintle 5 142. Afconnecting-rod 143 joins pintle 142 with a second pintle l i'lcarried on the end of the bracket 52. By I l sliding plate l llon drum 1% in the direction of the .slots in. the former, the radius of rotation ofpintle .142,

and hence the amplitude of oscillatiion'of bracket 42,"

may be adjusted.

. 1 Motor 52"is"shown in FIG URE Z-to'be mounted .on a table shelf; 4d; and is arranged to drive a shaft 145.

through a pulley 14s, a belt 147, and a furtherfipulley "15th carried on one .end of the shaft, which is supported .in;

pillow blocks 151 and 152. Secured-to the other'end-of the shaft'lidS, asis better shown in FIGUREIO, is .a 'cross'mentber l53fhavingoppositely. extending arms tion members mounted .on' theconverging ends of a like plurality of horizontal shafts radial to 'theosphere to engage the surface thereof .at areascentered; at I points; substantially equally spaced about-a great circlethere of; means causing. rotation :of said. members iabout: the aXes of said shafts .at independently adjustable rates; and 'means causing angular oscillation of one; of 'said' shafts, in a horizontall plane, about the center of-the sphere; 7

Means for causing random-,rotation of a sphere comprising, 'in combination; a .plunality of' hollow friction members. mounted on the'converging ends of a like plurality of horizontal shafts radialto thesphere to engage the surface .thereof at areas centered: at points substantially ,equally spaced about a. great c ircle thereof;- *means causing-rotation of saidniembers about the axes of saidshafts at independently adjustable rates; and

I Now, the remaining motors are set in opera- 7 tion and random rotation of the sphere in the laps. takes a place. ing the'tension in springs34, 35, and-Blithe speed of plurality of horizontal shafts radial to the sphere to. engage the surface thereof at areas centered at points substantially equally spaced about a great circle thereof; means causing rotation of said members about the axes of said shafts at independently adjustable rates; means causing angular oscillation of one of said shafts, in a horizontal plane, about the center of the sphere; and means resiliently acting on another of said shafts to tend to displace it angularly from itstnormal radial orienta- Y tion relation to said sphere.

4. Means for causing random rotation of a sphere comprising, in combination: a plurality of hollow friction members mounted on the converging ends of a like plurality of horizontal shafts radial to the sphere to engage the surface thereof at areas centered at points substantially equally spaced about a great circle thereof; means causing rotation of said members about the axes of said shafts at independently adjustable rates; means causing angular oscillation of one of said shafts, in a horizontal plane, about the center of the sphere; means resiliently acting on another of said shafts to tend to displace it angularly from its normal radial orientation relation to said sphere; and means for projecting fluid upwardly to impinge upon the unsupported lowermost surface of the sphere.

5. In combination: a container having side walls an a bottom including a peripheral downwardly slanting port-ion and a central open portion; a flexible diaphragm of resilient material closing said open portion; a metallic tongue underlying said diaphragm; and rapping means operable to impact said tongue from below so as to splash fluid in said container upwardly at the center thereof.

6. In combination: a shaft; a collar on said shaft; a bushing receiving said shaft for relative movement therebetween; inner and outer gimbal rings mounting said bushing for limited rotation about each of a pair of axes normally perpendicular to each other and to the axis of said shaft; means mounting said outer gimbal ring for rotation about an axis normally aligned with the axis of said shaft; and resilient means connecting said collar to said bushing for positioning said shaft axially with respect to said bushing and for transmitting rotation from said bushing to said shaft.

7. In combination: a shaft; a collar on said shaft; a bushing receiving said shaft for relative movement therebetween; inner and outer gimbal rings mounting said bushing for limited rotation about each of a pair of axes normally perpendicular to each other and to the axis of said shaft; means mounting said outer gimbal ring for rotation about an axis normally aligned with the axis of said shaft; a radially resilient member carried on said' shaft; a hollow member having an inner circular wall of substantially the radius swept by said resilient member as a result of rotation of said shaft; adjustable means mounting said hollow member for engagement by said resilient member; and means for adjusting said adjustable means to vary the eccentricity of said circular wall with respect to the axis of rotation of said shaft, to apply a transverse bias force thereto which varies as said shaft rotates.

8. The method of lapping a convex spherical body which comprises supporting the body solely in several hollow laps rotatable about intersecting substantially horizontal axes, causing rotation of said laps about saidaxes at predetermined rates, and causing independent rotation about their respective axes and for limited pivotal movement about said further points, so that the axes of all three shafts are normally coplanar and normally intersect at said first point; hollow laps mounted at the ends of said shafts which are directed toward said first point; resilient means normally urging said shafts toward said first point so .that a sphere of predetermined radius may be supported solely in said laps; means for causing said rotation of said shafts at predetermined speeds and in predetermined directions; and means for causing continuous limited angular oscillation of said first shaft in said horizontal plane about said first point as a center.

10. In combination: a first shaft having a horizontal axis passing through a first point; means mounting said first shaft for translation along and rotation about said horizontal axis; a pair of further shafts having axes passing through a pair of further points lying in the horizontal plane containing said horizontal axis; means mounting said further shafts for translation along and rotation about their respective axes and for limited pivotal movement about said further points, so that the axes of all three shafts are normally coplanar and normally intersect at said first point; hollow laps mounted at the ends of said shafts which are directed toward said first point; resilient means normally urging said shafts toward said first point so that a sphere of predetermined radius may be supported solely'in .said laps; means for causing said rotation of said shafts at predetermined speeds and in predetermined directions; and means for causing continuous limited angular oscillation of said first shaft in said horizontal plane about said first point as a center.

11. In combination: a first shaft having a horizontal axis passing through a first point; means mounting said first shaft for translation along and rotation about said horizontal axis; a plurality of further shafts having axes passing through a plurality of further points lying in the horizontal plane containing said horizontal axis, the angles between adjacent pairs of said axes being normally substantially equal; means mounting said further shafts for translation along and rotation about their respective axes and for limited pivotal movement about said further points, so that the axes of all three shafts are normally coplanar and normally intersect at said first point; hollow laps mounted at the ends of saidshafts which are directed toward said first point; resilient means normally urging said shafts toward said first point so that a sphere of predetermined radius may be supported solely in said laps; means for causing said rotation of said shaftsv at predetermined speeds and in predetermined directions; and means for causing continuous limited angular oscillation of said first shaft in said horizontal plane about said first point as a center.

12. In combination: a first shaft having a horizontal axis passing through a first point; means mounting said first shaft for translation along and rotation about said horizontal axis; a plurality of further shafts having axes angular oscillation of one of the laps, in the horizontal plane, about the point of intersection of the axes as a first shaft for translation along and rotation about said horizontal axis; a plurality of further-shafts havingaxes passing'through a plurality of further points lying in the horizontal plane containing said horizontal axis; means mounting said further shafts for translation along and passing through a plurality of further points lying in the horizontal plane containing said horizontal axis; means mounting said further shafts for translation. along and rotation about their respective axes and for limited pivotal movement about said further points,so that the axes of all three shafts are normally coplanar and normally intersect at said first point; hollow laps mounted at the ends of said shafts which are directed toward said first point; resilient means normally urging said shafts toward said first point so that a sphere of predetermined radius may be supported solely in said laps; means including said resilient means for causing said rotation of said shafts at predetermined speeds and in predetermined directions; and means for causing continuous limited angular oscillation of said first shaft in said horizontal plane about said rotation about their respective axes and for limited pivotal movement about said further points, sothattthe axes of all three shafts are normally coplanar 'and'normally intersect at'said first point; hollow laps mounted at-the ends of said shafts which are directed toward said" first point; resilient means normally urging said shafts toward said first point so that a sphere of predetermined horizontal axis; a plurality of further shafts having axes passing through a plurality of further points lying in the. horizontal plane containing said horizontal axis; means mounting said further shafts for translation along and axesof'all'three shafts are normally coplanar and normally intersectat said first point; hollow: laps mounted at the endsof said shafts which are directed toward said first point; resilient means normallyfurgingsaid shafts toward said first point so that a sphere of predetermined radius may be supported, solely in said laps';tmeans for causing (said rotation .of said shafts at predetermined speeds and in predetermineddirections; "means for causing contimiouslimited angular oscillation of" said first shaft radius maybe supported solely in-said laps; means for 1 s causing said rotation of said shafts at predetermined speeds-and in predetermined directions; .mea:ns for causing oontinuouslimited angular oscillation of said first shaft in said horizontal plane about said first point as a center; and means for continuously supplying lapping.

slurry to a phere suspended in said laps.

'14. In combination: a first shaft having a horizontal axis passing through a first point; means mounting said first shaft for translation along and rotation about said horizontal axis; a plurality of further shafts having axes passing through a plurality of further points lying in the 7 horizontal plane containing said horizontal axis; means mounting said further shafts 'for translation along and rotation about their respective axes and for limited piv-i otal movement about said further points, so that the in said horizontal plane about said first point as a center; and means supplying abiasing force to one of said further shafts tending to rotate it, aboutithe' associated further-point, away from the position in which it passes.

said first point. V e

References 'Qited in the file of this patent UNITED STATES PATENTS V v Mushkin Mar. 

1. MEANS FOR CAUSING RANDOM ROTATION OF A SPHERE COMPRISING, IN COMBINATION: A PLURALITY OF HOLLOW FRICTION MEMBERS MOUNTED ON THE CONVERGING ENDS OF A LIKE PLURALITY OF HORIZONTAL SHAFTS RADIAL TO THE SPHERE TO ENGAGE THE SURFACE THEREOF AT AREAS CENTERED AT POINTS SUBSTANTIALLY EQUALLY SPACED ABOUT A GREAT CIRCLE THEREOF; MEANS CAUSING ROTATION OF SAID MEMBERS ABOUT THE AXES OF SAID SHAFTS AT INDEPENDENTLY ADJUSTABLE RATES; AND MEANS CAUSING ANGULAR OSCILLATION OF ONE OF SAID SHAFTS, IN A HORIZONTAL PLANE, ABOUT THE CENTER OF THE SPHERE. 